26 June 2012

3 minute read

Oceania

Segregating breeders in northern Australian herds can enhance cow body condition at critical times to increase re-conception rates, decrease overheads and operating costs, and tighten the calving period to produce fewer lighter heifers at first mating.

Mt Isa cattle veterinarian Ian Braithwaite said introducing a breeder segregation system to manage cows that calved out of season (from May to October) could lift weaning percentages by 25 per cent a year for the ensuing four years.

“In more extensive areas of northern Australia, bulls are run year round, but calving windows can be controlled through preg testing, foetal ageing and segregation without bull removal,” Ian said.

“Out-of-season calvers lose body condition fairly markedly because they are calving down when pasture nutrition is declining, and have difficulty raising calves. We see higher mortalities in this group.

“To identify this group and market them for cash flow minimises the problem and generates first-round income.”

The initial steps are to segregate wet and dry cows at first-round muster, around the end of the growing season (March–April), and to manage each mob separately.

“(Without segregation) you have to look after every cow in the herd to feed the out-of-season calvers, which is costly. If you keep them separate, you can target your efforts for that group of cows,” Ian said.

Each year, producers need to decide whether to cull or keep the out-of-season calving mob. If sufficient pasture is available, the late calvers can be kept segregated and unweaned until the break of season, at the end of the year.

Ian said this would let the lactating cow’s body condition score slip to around 2.5 and interrupt cycling. After weaning, the cow regains body condition and re-commences cycling.

The timing of weaning for segregated out-of-season calvers is critical to bring them back in line with the ideal calving group.

Pregnancy testing the segregated group helps to identify the worst reproductive performers.

Producers with good replacement heifers can increase pressure on fertility by culling all cows that lose a calf between pregnancy testing and branding, regardless of how the calf may have been lost.

Ian said that he could lift weaning rates by 25 per cent on four-year rolling averages for businesses not using these systems, which he likened to bringing on an entire weaning crop every four years.

“Once I paddock 1,000 cows, pregnancy tested in calf (PTIC), I’ll guarantee 85 per cent weaning,” he said (ie a 15 per cent calf loss between preg test and weaning).

“If we’ve identified 1,000 PTIC cows to calve by a certain time, and only 650 come in with a weaner, we’re starting to use the system to identify animal production issues like disease or predation.”

Saving feed supplement costs can be a lucrative spin-off from managing out-of-seasons calvers as a separate mob, without affecting re-conception rates. In herds of 10,000 breeders, Ian recalled savings of up to A$500,000 a year. Reducing the calving window from 12 months to seven months and using foetal ageing information gives business predictability and helps identify marketable animals up to a year ahead.

In addition, Ian said that replacement heifers taken from a shorter calving window were a lot better grown, meaning fewer lighter heifers at joining and improved first-time conception rates.

Essential requirements for a successful breeder segregation system include an effective heifer replacement program, some basic infrastructure to keep breeders separated and a careful plan to manage the various mobs.

“Even with basic infrastructure these systems will work, but a producer who can save A$200,000 in supplementation costs can afford to invest a little more in infrastructure,” Ian said.

TheCattleSite News Desk